(1) Field of the Invention
The present invention relates to physical chemistry and, more particularly, to porous carbonaceous materials.
The present invention can be useful in the production of carbon adsorbents and catalysts for various chemical processes.
(2) Description of the Related Art
Known in the art are porous carbonaceous materials-active carbons employed as carriers and adsorbents. Active carbons are produced from charcoal by way of moulding thereof with a binder, followed by carbonization of the binder and a high-temperature vapour-gas activation. For example, large-size carbon particles with a low specific surface area are mixed with disintegrated coal pitch. The mixture is granulated in the form of beads, dried, carbonized and activated by steam. Such active carbons have but limited applications as carriers and adsorbents due to low mechanical-strength characteristics, a high content of ash and a broad pore-size distribution with a high proportion of pores with a size of less than 20 .ANG. (U.S., A, No. 3533961).
Known in the art is a porous carbonaceous material comprising a three-dimentional matrix formed by spherically-shaped particles of carbon black bonded by a carbonaceous binder. The porous carbonaceous material has a pore volume of at least 0.2 cm.sup.3 /g, a specific surface area of over 100 m.sup.2 /g, a narrow pore size distribution in which at least 45% of their total surface area are accounted for by pores with a size of 20 .ANG. and more, and the distribution maximum is within the range of 40 to 60 .ANG. (U.S., A, No. 4029600).
This prior art carbonaceous material has a disadvantage residing in a low mechanical strength comparable with that of active carbons. The mechanical strength of a carbonaceous material at a binder content of up to 50% by mass exceeds that of granulated carbon black without a binder only by 6-6.5 times. Furthermore, impurities can be introduced into the carbonaceous material in the preparation thereof along with the binder. In particular, a binder based on polymers of furfuryl alcohol can also incorporate sulphur which is a strong catalytic poison. In the known carbonaceous material pores with a size of 20 to 200 .ANG. account for 40% of the specific surface area. However, the reference teaches that the maximum of pore size distribution is within the range of from 25 to 190 .ANG.. Therefore, the known carbonaceous material has lower mechanical strength characteristics and a smaller volume of pores with a size above 200 .ANG. that play an important role in processes of mass transfer in catalysis and absorption.